Apparatus and method for forming inside surface of tube stock

ABSTRACT

A method for forming a smooth cylindrical inside wall of a tube is described. The tube is heated and a shaped arbor is inserted into the tube. The tube is forced against the arbor to shape the interior of the tube in general conformity to the arbor and the arbor is removed. The tube may be cut into several sections shaped to be useful as tapered roller bearing cups.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application Ser. No. 60/715,340 filed Sep. 8, 2005.

BACKGROUND OF THE INVENTION

This invention relates generally to metal forming and more particularly to preparing tubing for manufacture of outer races for tapered roller bearings.

Various ways are known to make outer bearing races (usually referred to as “cups”) for tapered roller bearings. Typically they involve using a seamless tube made of steel and cross-cutting it into rings followed by machining the rings to form a smooth cylindrical outside diameter (O.D.) and a conical I.D. One of the known ways to cut the tube into rings is to use a gang saw as disclosed in U.S. Pat. No. 5,293,794 issued to Mosey et al. on Mar. 15, 1994. That saw provides an advantage over prior saws in that the amount of tube material lost due to the kurf of sawblades with prior equipment was reduced, so that more rings can be produced from a length of tubing. There remains an interest in optimizing the production of useful parts from a length of tubing.

According to one feature of my invention, instead of a smooth cylindrical inside wall of the tube, it is treated to reduce the amount of material removal which would otherwise occur in the machining of the bearing cups produced from the tube. Another feature is forming the interior surface of the tube into a shape similar to the desired shape for the bearing cup I.D.

Another feature is roll forming of the shape.

SUMMARY OF THE INVENTION

In one embodiment of the present invention, instead of a smooth cylindrical inside wall of the tube, it is treated to reduce the amount of material removal which would otherwise occur in the machining of the bearing cups produced from the tube.

Another feature of the present invention is forming the interior surface of the tube into a shape similar to the desired shape for the bearing cup I.D.

Another feature of the present invention is roll forming of the shape.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a cross-sectional view showing the one embodiment of the invention.

FIG. 2 is a schematic showing the orientation of the tool of the two rolls.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings, and specific language will be used to describe that embodiment. It will nevertheless be understood that no limitation of the scope of the invention is intended. Alterations and modifications in the illustrated device, and further applications of the principles of the invention as illustrated therein, as would normally occur to one skilled in the art to which the invention relates are contemplated, are desired to be protected. In particular, although the invention is discussed in terms of a blood glucose meter, it is contemplated that the invention can be used with devices for measuring other analytes and other sample types. Such alternative embodiments require certain adaptations to the embodiments discussed herein that would be obvious to those skilled in the art.

Referring now to the attached drawing, a pair of rolls 11 and 12 in a tube rolling mill are shown having received a pierced seamless tube shell 13 between them. An arbor 14 is provided inside the tube. The rolls themselves are conical from their ends toward a circular crown area such as 16, and are skewed as show at 11A in FIG. 2 for the roll 11 and 12A for roll 12. Therefore, as the leading end of tube 13 along with the leading of arbor 14 are introduced simultaneously in the direction of arrow between the rotating rolls, they will advance the tube in the direction of arrow of 17.

Briefly stated, the shaped arbor 14 is introduced into the trailing end of a pierced seamless tube shell heated to 2,250 degrees Fahrenheit. The arbor length will be the length of the tube plus approximately 20% projecting out the tail end of the tube because, as the tube is processed through the rolls, it will become elongated. In an elongating mill or like mill and setting the roll gap smaller than the shell outside diameter (O.D.), the shell is forced down onto the shaped arbor. The arbor is circular about a longitudinal axis 18 which is also the axis of the tube 13. As the rolls turn and being skewed as they are, advance the tube shell, the shell will go into the rolls round and be squeezed oval as the rolls rotate it and move it against the arbor at the gap, rotating the arbor along with the tubing. As the tubing exits the roll gap, it expands radially to its original O.D. or slightly less. This results in an air gap 19 created between the outer surface of the arbor and the inner surface of the shell as the shell exits the rolls. After the entire tube has passed through the rolls, the arbor can be removed by simply pulling it out of the tube.

The completed tube can then be cross-cut at 21, 22 and 23, for example, to make two O-rings having conical inside faces which can then be lightly machined and ground or otherwise treated for finishing into a bearing cup. Thus it is seen that the arbor is shaped for a succession of generally conical faces in alternate directions of taper relative to the axis 18 to provide a series of alternating conical inside faces of the tube shell which can then be converted readily to bearing cup rings.

U.S. Pat. No. 5,406,820 issued to me on Apr. 18, 1995 discloses an organization of gripping rolls and material feed into such rolls. Other arrangements may also be used.

While the invention has been illustrated and described in detail in the drawings and foregoing description, the description is to be considered as illustrative and not restrictive in character. Only the preferred embodiment, and certain other embodiments deemed helpful in further explaining how to make or use the preferred embodiment, have been shown. All changes and modifications that come within the spirit of the invention are desired to be protected. 

1. A method of forming a smooth cylindrical inside wall of a tube useful for preparing tapered roller bearing cups, comprising: providing a tube heated to an elevated temperature sufficient to allow forming of the tube by pressing against a shaped arbor; inserting a shaped arbor into the tube; forcing the tube against the arbor to shape the interior of the tube in general conformity with the shaped arbor; and removing the shaped arbor from the tube.
 2. The method of claim 1 and which further comprises cutting the tube into several sections shaped to be useful as tapered roller bearing cups. 